Cappello A, Gnudi G, Lamberti C
Department of Electronics Informatics and Systems (DEIS), University of Bologna, Italy.
Ann Biomed Eng. 1995 Mar-Apr;23(2):164-77. doi: 10.1007/BF02368323.
A new one-step computational procedure is presented for estimating the parameters of the nonlinear three-element windkessel model of the arterial system incorporating a pressure-dependent compliance. The data required are pulsatile aortic pressure and flow. The basic assumptions are a steady-state periodic regime and a purely elastic compliant element. By stating two conditions, zero mean flow and zero mean power in the compliant element, peripheral and characteristic resistances are determined through simple closed form formulas as functions of mean values of the square of aortic pressure, the square of aortic flow, and the product of aortic pressure with aortic flow. The pressure across as well as the flow through the compliant element can be then obtained so allowing the calculation of volume variation and compliance as functions of pressure. The feasibility of this method is studied by applying it to both simulated and experimental data relative to different circulatory conditions and comparing the results with those obtained by an iterative parameter optimization algorithm and with the actual values when available. The conclusion is that the proposed method appears to be effective in identifying the three-element windkessel even in the case of nonlinear compliance.
提出了一种新的一步计算程序，用于估计包含压力依赖性顺应性的动脉系统非线性三元件风箱模型的参数。所需数据为搏动性主动脉压力和流量。基本假设为稳态周期性状态和纯弹性顺应性元件。通过陈述两个条件，即顺应性元件中的平均流量为零和平均功率为零，外周阻力和特征阻力可通过简单的闭式公式确定，这些公式是主动脉压力平方、主动脉流量平方以及主动脉压力与主动脉流量乘积的平均值的函数。然后可以获得顺应性元件两端的压力以及通过该元件的流量，从而能够计算体积变化和作为压力函数的顺应性。通过将该方法应用于相对于不同循环条件的模拟数据和实验数据，并将结果与通过迭代参数优化算法获得的结果以及在可用时与实际值进行比较，研究了该方法的可行性。结论是，即使在顺应性为非线性的情况下，所提出的方法在识别三元件风箱方面似乎也是有效的。
